1 SEA-GRASS EPIPHYTES (“HANGERS-ON”) AT A GLANCE BACKGROUND Sea-grasses are grass-like, aquatic, flowering plants, 4. with true leaves, stems and roots. They grow in sand and mud (sedimentary aquatic environments, or soft “bottoms”) trapping sediment, their horizontal stems helping to prevent mobile substrates from 4. washing away during storms. Algae require harder, stable surfaces on which to 2. grow – they attach to rock (hard “bottoms”), shells, port structures such as jetty piles or even ships hulls. In addition, some algae and also some animal colonies either preferentially or incidentally grow permanently attached to already-established algae or sea-grasses, a “lifestyle” or niche called epiphytism. The series of pictures below is designed to introduce you to some sea-grass epiphytes of southern Australian seas. Certainly not all of them, as there may be as many as 117 algal species according to 1. one worker.1. Also, small, mobile animals that graze microscopic films of living organisms that grow on sea-grasses, are not included. Below, you will find pictures of only the commonest and more easily observable epiphytes, posted as a series of panels containing similar-looking organisms. To locate the sea-grasses that act as substrates for them, go to Pictured Keys.....-Major Groups - sea grasses, on this Website
FACTS ABOUT SEA-GRASS EPIPHYTES • 1.most attach to the surface of sea-grasses and do not use them for nutrition (however, for parasites and intimate 3. anatomical connections, see Algal intimates, on this website) • 1.in some sea-grass meadows, epiphytes may be only 25% of the total weighable material (the biomass) but perform more algal epiphytes on a pressed than 60% of the photosynthesis (the productivity) • 2.sea-grasses host similar epiphytes specimen of the sea-grass Amphibolis • some epiphytes prefer shallow water communities, others the antarctica at the State Herbarium of plant tips, some the jointed parts of the stem South Australia. • 3.epiphytes harbor a diverse community of cryptic crustaceans and molluscs that are food for economically important fish - on stems species as well as being themselves fish food 1. coralline, jointed Red alga • 4.unfortunately, epiphytes may grow so densely, particularly 2. “fluffy” Red alga if plant nutrients are released into coastal waters from sewage outfalls, they smother their host sea-grasses. For example, 3. narrow-branched Red alga some 4,000 - 5,000 ha of sea-grass meadows have been lost - on leaves along metropolitan Adelaide S.A. coastline as a consequence 4. white, scaly, coralline Red alga of over-supply (eutrophication) of nutrients • because they are small and inconspicuous, many epiphytes may be undescribed – these are called cryptic species
Wiry Sea nymph, Amphibolis in 2m of water, Cape Jervis SA. Twisted leaves arise from upright Broad-leaved Tape-grass, Posidonia in sand at stems. Horizontal runners have collected sediment Sea-grass meadows at Encounter Bay SA, about 1m 20m depth, the “Hotspot” West Coast SA. The forming a bank about 400 mm tall. The warty deep: horizontal stem or runner connecting the two tufts brown alga Scaberia is growing attached to pebbles broad-leaved Tape-grass, Posidonia at left, of leaves is buried beneath the coarse sand in an eroded part of the bank at right narrow-leaved Eel grass, Heterozostera on the right
The panels below illustrate only Some useful terms epiphytes large enough to be discerned in forked ! (dichot- the field, that is, larger than about 10 mm omous) in total length. For some of the smaller, flat- bladed and inconspicuous epiphytes usually filamentous flat-branching needing magnification, see Groups at a glance: marine plant crusts, stains, scums foliose and scales and also Turf and fouling algae. I-III on this Website. encrusting saccate pinnate/ in 2 rows
Baldock, R N (2020). Seagrass epiphytes at a glance. 26 pp. Algae Revealed. Adelaide: State Herbarium of South Australia flora.sa.gov.au/algae_revealed 2
SCALE, MICROSCOPE VIEWS, NAMES AND FOLLOW-UP SEARCHES The coin used as a scale is 24 mm or almost 1” across. Unless acknowledged otherwise, all images have been made by the author and come from pressed specimens or the extensive slide collection of the algal unit, State Herbarium of S Australia, collections generated by the late Professor Womersley and his workers over some 60 years. Images with dark backgrounds have been taken using phase contrast or interference microscopy to highlight transparent structures. Other images may be stained dark blue. Scientific names follow those found in Womersley, H B S. (1984 - 1988). The Marine Benthic Flora of southern Australia Parts I- III as it continues to provide the most comprehensive and accessible account. Recent name changes can be found in https://algaebase.org/ The many references for following up identifications made in the Panels below can be found in the Website http://www.flora.sa.gov.au/algae_revealed/index.shtml Adelaide: State Herbarium of South Australia, 2009 – 2020.
ACKNOWLEDGEMENT Thanks to Carolyn Ricci of the State Herbarium of South Australia who gave helpful advice as to the format and content of this publication, gathered some of the specimens together and also edited the material.
plants or SEARCH animals permanently STRATEGY attached to sea-grasses
generally colourless, grey or generally coloured unless transparent, feathery, in thin bleached white from lines, with patterned scales exposure to the sun or coral-like or in shells
brown, some slimy & worm- generally not brown, ANIMALS like, flat or narrow-branched but dark or bright go to panel #A, pages 3-5 BROWN ALGAE green, pink, dark red go to panel #B, pages 6-11
generally bright or dark green, lettuce-like or thread-like A4 B5 GREEN ALGAE & BLUE- A1 BRYOZOANS plants GREEN ALGAE A2 A3 SPONGES pages 4, 5 worm-like go to panel #G, pages 12, 13 page 3 HYDROIDS SPIRORBIDS pink or red, fluffy, or thread- pages 3, 4 page 4 like, or narrow-branched, or B1 B4 lettuce-like; or limey and G2 plants hollow, plants crunchy hollow G3 balloon-shaped filamentous RED ALGAE page 12 foliose page 6 pages 10, 11 G1 B2 B3 go to panel #R, pages 14-26 page 13 filamentous plants flat- plants tufted, page 12 branched wiry R1 pages 7, 8 page 9 filamentous G4 R2 R5 blue-green pages 14-18 coralline narrow- algae pages 25, 26 branched page 13 pages 19-21 R3 R4 ribbon & broad- bead-like bladed pages 24 pages 22, 23 LITERATURE 1. Borowitzka M.A. and Lethbridge R.C. (1989) Seagrass epiphytes. In: Larkum AWD, McComb AJ and Shepherd SA (eds) Seagrasses: With Special Reference to the Australasian Region, pp 458–499. Elsevier/North Holland, Amsterdam 2. Johnson J. E. (1973) A study of the algal epiphytes on the seagrass Posidonia australis Hook. f. in two areas along the southern Australian coast. MS 3. Bloomfield, A.L. & Gillanders, B.M. (2005) Fish and invertebrate assemblages in seagrass, mangrove, saltmarsh, and nonvegetated habitats. Estuaries 28, 63–77.10.1007
4. Westphalen, G et al (2005) A review of seagrass loss on the Adelaide metropolitan coastline. Adelaide coastal waters study. Technical Report Number 2.
EPA, Adelaide 5. common name suggested by Edgar, G J (2008). Australian marine life. Th e plants and animals of temperate waters. Sydney, New Holland 6. Gowlett-Holmes, K (2008). A field guide to the marine invertebrates of South Australia. Sandy Bay, Tasmania. Notomares 7. Womersley, H B S & Baldock R N (2003). The Encounter 2002 expedition to the Isles of St Francis, South Australia: marine benthic algae. Trans R Soc SA (2003) 127 (2) 141:151
8. Harvey, A et al (2005). Coralline algae of central New Zealand. An identification guide to common “crustose” species. NIWA Information Series No. 57 9. Bock, P E (1982) Chapter 9. in Shepherd S A & Thomas I M. Marine Invertebrates of Southern Australia Part I. Adelaide, Government Printer. See also The Bryozoa Home Page www.bryoza.net 10. Shepherd, S A & I M Thomas (Eds) (1982). Marine invertebrates of southern Australia. Part I. Adelaide, Government Printer
Baldock, R N (2020). Seagrass epiphytes at a glance. 26 pp. Algae Revealed. Adelaide: State Herbarium of South Australia flora.sa.gov.au/algae_revealed 3
PANEL A: ANIMALS
A1: SPONGES 6,10. irregular masses on sea-grass stems, often punctured with visible but tiny pores, and with a rough texture due to the needle-
like internal skeleton
RRight: one of many possible sponges that grow on sea-grass stems Far right, above: magnified view, tiny pores visible
Far right, below: sponge skeleton of spicules, in this example, made of limey material that dissolves in acid Other sponges have spicules made of glassy material that is not acid soluble
A2: HYDROIDS 10. minute hydra-like individuals (polyps) living in cups in small or large, flexible
colonies
A2.1: pinnate colonies, polyps on opposite sides of flexible branches
pinnate/ in 2
rows
hyd hyd Stereotheca elongata hyd hyd 1. many hyd Elongate seagrass hydroid hyd on the sea-grass Amphibolis griffithii pinnate hyd gon hyd • cups holding feeding polyps colonies (hydrothecae, hyd) occur on both on the sea- sides of the “stem” bearing them, grass stem about 5 teeth at the rims, their bases sunken into the “stem” • large reproductive cups (gonotheca, gon) have prominent “horns”
A2.2: colonies creeping on sea- grass (also algal) hyd surfaces, polyps on one hyd side of branches on stalks
rh ho
gon nem
st
hyd Campanularia sp • host (ho) • creeping runner (hydrorhiza, rh) • cups holding feeding polyps (hydrothecae, hyd) ho • large reproductive cup (gonotheca, gon) • chain containing minute stinging individuals (nematothecae, nem) Panel A continued next page • stalk (st) with wavy margins diagnostic of the genus 1.One study places the following Bryozoans (not illustrated above) as common on sea-grass stems:- Adeonellopsis portmarina,, Pyripora polita
Baldock, R N (2020). Seagrass epiphytes at a glance. 26 pp. Algae Revealed. Adelaide: State Herbarium of South Australia flora.sa.gov.au/algae_revealed 4
A2.3: polyps on one side of hyd Plumularia filicaulis side branches, partly embedded in them or
on short jointed stalks hyd
Plumularia flexuosa
Plumularia sp nem #1, #2
hyd hyd • cups holding feeding polyps (hydrothecae, hyd) hyd • paired stinging individuals (nematothecae, nem #1, #2) at rim of hydrotheca gon • large reproductive cup Plumularia flexuosa (gonotheca, gon)
A3: SPIRORBIDS 6. spiral, limey tubes, about 1 Left: Metalaeospira tenuis, formerly mm across, sometimes in Janua sp, with tight clockwise great number, flat on 1 mm spiral. An almost identical surfaces of sea-grasses species, Neodexiospira also occurs, and has an anti- 6. clockwise spiral to its shell
A4: BRYOZOANS 9. limey or horny colonies punctured with small pores;
cups containing the individual animals often with lids and spines
bryozoan examples: Above: unknown colony with horned zooid cups Above, right: Microporella; cups with coloured lids
bryozoan examples: Left, and above: two magnifications of Corbullela Right: A4.1: encrusting Bryozoan, probably Electra flagellum (on the Red alga Rhodymenia foliifera but also 1.found on seagrass leaves)
Baldock, R N (2020). Seagrass epiphytes at a glance. 26 pp. Algae Revealed. Adelaide: State Herbarium of South Australia flora.sa.gov.au/algae_revealed 5
A4.2: Celleporaria cristata Above: two magnifications of a colony of an undulate nodule of calcified cups, some still with intact horns at the margins
of their orifice, wrapped around the stem of a pressed specimen of the sea-grass, Amphibolis antarctica
A4.3: ?Densipora corrugata Right: detail of an eroded, nodular colony wrapped
about the stem of Amphibolis antarctica. The colonies of this species and Celleporaria cristata are very 9.similar, and require detailed examination of the cups to separate them
A4.4: Thairopora cincta
Above: two magnifications of a colony, fractured in places, wrapped about the stem of Amphibolis antarctica. The zooid cups form distinctive rings about the stem
Baldock, R N (2020). Seagrass epiphytes at a glance. 26 pp. Algae Revealed. Adelaide: State Herbarium of South Australia flora.sa.gov.au/algae_revealed 6
PANEL B: BROWN ALGAE - PHAEOPHYTA
B1: PLANTS HOLLOW, BALLOON-SHAPED (SACCATE)
also found in Pictured keys: .....
hollow Brown algae shaped like
bubbles, balloons or thin tubes
B1.1 Asperococcus 2 species
on Posidonia sea-grass
Asperococcus bullosus Right: several pressed plants on a sea- grass leaf Below, left: two plants showing characteristic “puckering” of the tubular plant bodies Below, centre: surface microscopic view, spore patches (sori, so)
so so
so
Above: Asperococcus fistulosus (above) on Zostera sea-grass
B1.2 Colpomenia species ball-shaped, wrinkled and
often with the surface layer torn; three species possible, identified from features of the hair patches on the surface of
the plant body
Above: two plants of Colpomenia Above: surface view of patches of spores of Below: many plants strung along a Colpomenia peregrina sea-grass stem
Panel B continued next page
Baldock, R N (2020). Seagrass epiphytes at a glance. 26 pp. Algae Revealed. Adelaide: State Herbarium of South Australia flora.sa.gov.au/algae_revealed 7
B2: PLANTS FLAT-BRANCHED –
FAMILY: DICTYOTACEAE also found in Groups at a glance: Dictyotaceae
B2.1: Zonaria turneriana occurs on Amphibolis sea-grass
Right: tips of a plant, flat forked blades Far right: microscopic surface view, cells stained blue: cells in rows, in groups of 2-4
B2.2:
Dictyopteris muelleri occurs on Amphibolis sea-grass. Below: two magnifications of plants, prominent mid-rib, spore patches scattered
B2.3:
Lobospira bicuspidata
Left: tendrils found at the plant base attach the plant to the host Centre: branches densely clothed with tiny, twisted, pointed blades Right: detail of blades, each with a pair of apical points
Panel B continued next page
Baldock, R N (2020). Seagrass epiphytes at a glance. 26pp. Algae Revealed. Adelaide: State Herbarium of South Australia flora.sa.gov.au/algae_revealed 8
B2.4: Glossophora nigricans on Amphibolis sea-grass
Left: microscopic surface view, stained blue. Protrusions making the surface appear rough Far right: whole plant
B2.5: Pachydictyon paniculatum on Amphibolis sea-grass
10 mm
Pachydictyon paniculatum Above: cross section: Right: whole plant
B2.6: Dilophus angustatus on Posidonia sea-grass
Immediate right: whole plants on a seagrass leaf Far right, above: cross section; blade edge 2-3 cells thick Far right, below: microscopic surface view of blade tip, single tip-cell protruding
B3: PLANTS FLAT-BRANCHED FAMILY- PUNCTARIACEAE
Punctaria latifolia on Amphibolis sea-grass
Right: whole plants on a sea-grass stem Far right: cross section showing similar sized vegetative cells throughout the section, and small clusters of deeply-stained sporangia
Panel B continued next page
Baldock, R N (2020). Seagrass epiphytes at a glance. 26pp. Algae Revealed. Adelaide: State Herbarium of South Australia flora.sa.gov.au/algae_revealed 9
B4: PLANTS TUFTED, WIRY see also Pictured keys .... wiry brown alga in this Website
B4.1: Phloiocaulon spectabile on Amphibolis sea-grass a c a c a c Right: whole plant Far right: microscopic views: apical cells (a c) dark and swollen; branches divided into segments (seg)
seg
B4.2: Carpomitra costata
on sea-grass
Right: whole plants
Far right: detail of tufted tips
B4.3: Sporochnus species on sea-grass;
there are 6 Sporochnus species that could be epiphytes of sea- grasses. The nature of the fertile side tufts is used to identify them.
Sporochnus pedunculatus from Marino Beach, SA
Right: whole plant
Far right: detail of short fertile branchlets ending
in a hair tuft
Panel B continued next page
Baldock, R N (2020). Seagrass epiphytes at a glance. 26pp. Algae Revealed. Adelaide: State Herbarium of South Australia flora.sa.gov.au/algae_revealed 10
B5: FILAMENTOUS BROWN ALGAE see also Pictured keys .... turf and fouling algae III thread and wormlike brown algae in this Website
B5.1: Sphacelaria spp Brown algae forming tufts, cells of filaments divided in bands or segments; many produce triangular-shaped packets of cells (propagules) seasonally, by which some species can be relatively easily identified. Only 3 of a possible 14 species are illustrated below.
Sphacelaria novae-hollandiae
Right: whole plants forming tufts
Far right: microscopic view of
branching pattern of
segmented filaments;
triangular propagule (pr) pr
Sphacelaria biradiata Right: microscopic view of segmented filaments; triangular propagule (pr) with long arms and a terminal hair Far right: whole plants forming tufts, on Posidonia pr
pr
Sphacelaria rigidula Left: whole plants forming tufts Centre: microscopic view of segmented pr pr filaments; triangular propagule (pr) with extremely long arms Far right: extracted propagule
Panel B continued next page
Baldock, R N (2020). Seagrass epiphytes at a glance. 26pp. Algae Revealed. Adelaide: State Herbarium of South Australia flora.sa.gov.au/algae_revealed 11
B5.2: Hincksia species (as Giffordia in the OTHER FILAMENTOUS BROWN ALGAL EPIPHYTES Marine Flora); commonly Hincksia ! OF SEAGRASSES sordida with the local name of “snot- examples: Ectocarpus, similar to Hincksia, and Elachista, Giraudia. grass” These are found largely as small tufts, <10 mm across, on sea-grass Plants form cloud-like masses, obscuring both sea- and algal surfaces, and are not illustrated below, but in grasses and large Brown algae, towards the end of summer, especially in SA Gulf waters. Fresh Turf and fouling algae. I-III on this website specimens feel slimy when handled Left: cloudy masses of Hincksia obscuring large Brown algae, at a cave occupied by a Giant Cuttlefish, Stony Point Spencer Gulf, SA Centre: pressed masses of Hincksia sp Right: branched filaments, two stalkless sporangia (sp)
B6: WORM-LIKE BROWN ALGAE also found in turf and fouling algae: III. thread and wormlike brown algae
B6.1: Polycerea nigrescens on Posidonia sea-grass
Left: chains of cells of a tissue squash of the surface layers (cortex) with diagnostic swollen tip cell Centre: plants on Posidonia leaves, slippery, and largely un-branched Right: dense growth on Posidonia leaf, plants with short side branches
B6.2: Cladosiphon filum on Posidonia sea-grass
Right: tissue squash of the surface layers (cortex) with diagnostic curved chains of cells Far right: whole plants on a sea-grass leaf
Baldock, R N (2020). Seagrass epiphytes at a glance. 26pp. Algae Revealed. Adelaide: State Herbarium of South Australia flora.sa.gov.au/algae_revealed 12
PANEL G: GREEN ALGAE (CHLOROPHYTA) AND
BLUE-GREEN ALGAE (CYANOPHYTA)
G1: FILAMENTOUS GREEN ALGAE
G1.1: Cladophora species. Also found in Groups at a Glance: Cladophora species groups I, II, IIA, IIB There are 19 species all of which are possible epiphytes of sea-grasses. Those illustrated below are
specifically listed in publications found in the Literature section on page 2.
Cladophora prolifera
Right: whole plant
Far right: microscopic detail of
elongate tip cell and
forks of branches
tending to be parallel
Cladophora vagabunda (as C. fascicularis on Posidonia in2.)
Left: stained microscope preparation showing rounded tip cells and branching tending to occur on one side of axes Right: whole plant
G2: HOLLOW GREEN ALGAE
§ G2.1: Enteromorpha species also found in ...... Ulva at a glance on this Website
Enteromorpha flexuosa Right: whole plant, found on Posidonia australis Far right: microscopic surface view of cells in lines and prominent single, clear structure (pyrenoid) in the chloroplast, characteristic of the species
§recent workers have merged Enteromorpha (in which the plant body is hollow) with Ulva, (in which the lettuce-leaf-like plant body is solid)
Panel G continued next page
Baldock, R N (2020). Seagrass epiphytes at a glance. 26pp. Algae Revealed. Adelaide: State Herbarium of South Australia flora.sa.gov.au/algae_revealed 13
G3: FOLIOSE (LETTUCE-LEAF -LIKE) GREEN ALGAE
G3.1: Ulva species also found in ...... Ulva at a glance on this Website
Ulva australis Right: whole plant, found on Amphibolis antarctica Far right, above: cross sections of two blades showing the 2 closely adhering layers of rectangular cells Far right, below: surface view of small cells in random, short lines
G3.2: Ulvaria species Two species are found in southern Australia. Unlike Ulva, blades are a single cell thick. Fuller descriptions can be found under ...... Green algae on this Website
Ulvaria oxysperma
Right: whole plant, found originally
attached to Amphibolis
antarctica
Far right:
surface view of small, angular
cells in random arrangement,
characteristic of the species
G4: BLUE-GREEN ALGAE - CYANOPHYTA. Also found in Pictured Keys ...... Blue-green algae
Rivularia polyotis colonies loosely attached to Heterozostera in shallow water, Encounter Bay SA
Left: colonies (arrowed) on Heterozostera Centre: detached, hollow colony Right: squash of the gelatinous wall of the colony. Extremely fine filaments (trichomes) of bacterial- sized cells, all pointing outwards, with basal, swollen specialist cell (heterocyst, arrowed)
Baldock, R N (2020). Seagrass epiphytes at a glance. 26pp. Algae Revealed. Adelaide: State Herbarium of South Australia flora.sa.gov.au/algae_revealed 14
PANEL R: RED ALGAE - RHODOPHYTA
R1: FILAMENTOUS RED ALGAE
R1.1: Anotrichium tenuis
sp
sp
sp
whole plants side branch arising from the lower end of filament tip with dense rings of hairs and a cell (arrowed), a characteristic of the species immature, stalked spores (sp), also in rings
R1.2: Centroceros species there are several species (some unnamed), of which the commonest, C. clavulatum, is shown here
Left: several plants Centre: incurved tips backlit to highlight rings of cells at nodes (arrowed) and columns of cells between nodes Right: stained specimen, thorny cells and hairs prominent at nodes; sporangia present at nodes
R1.3: Ceramium species There are 17 possible epiphyte species of Ceramium, but only two 2.reported as epiphytes of sea-grasses namely
C. puberulum and C. shepherdii
Ceramium puberulum Right: whole plants on a Posidonia leaf Centre: details of multicellular spines, on outer side Right: backlit filament highlighting rows of of curved tips cells at nodes with minute hairs (arrowed)
Panel R continued next page
Baldock, R N (2020). Seagrass epiphytes at a glance. 26pp. Algae Revealed. Adelaide: State Herbarium of South Australia flora.sa.gov.au/algae_revealed 15
Ceramium shepherdii Right: whole plants on a Posidonia leaf Far right: detail of rings of prominent, multicellular hairs at nodes; deeply stained sporangia also present
gl
n
Ceramium australe
t sp Above: whole plants on Amphibolis stems n Above, right: magnified branches showing prominent banding fil c Right: detail of large cells of the central filament (fil c), bands of small cells at nodes (n), spores (terasporangia, t sp) on one side of filaments n fil c Far right: filament tips, bent inwards and touching apically, prominent glands (gl) immersed in nodal cells
R1.4: Polysiphonia species There are 27 possible Polysiphonia epiphytes of sea-grasses of which only P. decipiens has been 2.listed from two areas along the southern Australian coast (as P. nigrita).
sp
sp
Polysiphonia decipiens Top, left: whole plants Top, centre: hooked tendrils at plant base Top, right: plant tip; colourless, branched hairs (trichoblasts), bands of cells, finger-shaped clusters of spermatia (sp) Bottom, far left: cross section ; central filament, 7 encircling pericentral cells Bottom, left: tips denuded of trichoblasts, cells in bands
Panel R continued next page
Baldock, R N (2020). Seagrass epiphytes at a glance. 26pp. Algae Revealed. Adelaide: State Herbarium of South Australia flora.sa.gov.au/algae_revealed 16
1 2 3 ha ha
rh Polysiphonia amphibolis Left: whole plants on Amphibolis stems horizontal runner (rhizome, rh), erect branches detail of the characteristic pad (hapteron. ha) attaching the runner to the substrate; bands with rings of 4 cells (pericentrals, 1....), 3 in side view
R1.5: Herposiphonia species There are 6 possible epiphyte species of Herposiphonia. Each has a creeping, horizontal rhizome giving rise to short upright branches (of limited growth) that alternate in a definite sequence with branches capable of continued growth . For information on the group to which this genus belongs go to filamentous red algae : Part V
c fil
Above, left: Herposiphonia versicolor: plants on a sea-grass stem
Above, right: H. calothrix: tissue squash of branch displaying all 8 (pericentral) cells in a band, and the central filament (c fil) slightly displaced
H. filipendula : 2 branching sequences illustrated. Continually-growing branch (indeterminate growth, i g), branches of determinate growth (1-3) of a branch sequence
i g i g 3 3 2 1 1 2 i g i g i g
Panel R continued next page
Baldock, R N (2020). Seagrass epiphytes at a glance. 26pp. Algae Revealed. Adelaide: State Herbarium of South Australia flora.sa.gov.au/algae_revealed 17 R1.6: Antithamnion species There are 11 possible epiphyte species of Antithamnion. Each has opposite side branches and most have bright gland cells. Particular species can be found in Pictured keys.... filamentous red algae : Part III
c fil
Antithamnion hanovioides whole plants on an algal host central filament (c fil) of box-shaped, large cells; side branches; divergent pointed tips, typical opposite side branch clusters of the species; bright glands
R1.7: Wrangelia species There are several possible epiphyte species of Wrangelia. Go to Filamentous red algae.... Part II on this Website for further information. Wrangelia velutina on Amphibolis 7. has been recorded for the Isles of St Francis, SA.
2
1 3 c fil 5
4
Wrangelia nobilis: detail of “fluffy” branches central filament of large cells cross section, basal cells of just visible through enveloping 5 whorl branchlets (1-5) radiating whorl branchlets from the central filament (c fil)
R1.8: Heterosiphonia callithamnium
numerous “fluffy” plants on sea-grass leaves divergent side branches ending in pointed cells lance-shaped sporangial structures (stichidia)
R1.9: Gattya pinella and other members of the Tribe Crouanieae, Go to Filamentous red algae.... Part II on this Website. Right: plant on Amphibolis Centre: tips stained to show the 3 central filament, regular, 2 radiating whorl-branchlets (also extraneous filaments 1 extending from the main plant body are present) Far right: cross section, with three whorl-branchlets (1,2,3) radiating out from the central, large filament Panel R.1 continued next page
Baldock, R N (2020). Seagrass epiphytes at a glance. 26pp. Algae Revealed. Adelaide: State Herbarium of South Australia flora.sa.gov.au/algae_revealed 18
R1.11: Dipterosiphonia prorepens
sea-grass stems completely smothered by creeping branching pattern, bands of cells, mix of branches side view and a cross section plants of Dipterosiphonia prorepens short side branches with spores (sp) showing a ring of 5 cells
R1.12: Spongoclonium species S. australicum and S. fasciculatum have been recorded as sea-grass epiphytes.
rh ax t sp
rh rh t sp ax
t sp
ax
rh
Spongoclonium australicum Centre: main branch (axis, ax) of large cells producing Right: side branches, stalkless sporangia (t sp) Left: whole plants upward- & downward growing rhizoids (rh) from basal cells of side branches
Also found in Filamentous red algae …..Part IV: nodally corticated algae on this Website R1.13: Spyridia species
Right: shallow, sandy rock pool with Spyridia filamentosa, a common epiphyte of Sea-grasses bleached Eel-grass, Heterozostera in sand, exposed at low tide
green (unbleached) Eel-grass, in shallow water
bleached, fluffy Spyridia filamentosa obliterating the Above: Above: whole plant of Spyridia filamentosa Eel grass beneath it, in a corticated main branch (axis) and shallow pool with Tape-grass naked short side branches of (Posidonia) detritus Spyridia filamentosa
Panel R continued next page
Baldock, R N (2020). Seagrass epiphytes at a glance. 26pp. Algae Revealed. Adelaide: State Herbarium of South Australia flora.sa.gov.au/algae_revealed 19
R2: NARROW BRANCHED RED ALGAE – plants with firm surfaces
R2.1: Hypnea species
there are 4 species all of which are possible sea-grass epiphytes. To separate species go to Pictured keys: narrow branched red algae and Groups at a glance: Hypneaceae
Hypnea ramentacea whole plant Hypnea ramentacea detail of curled Hypnea charoides, numerous short spines tips to branches on main branches
R2.2: Laurencia forsteri trich there are 13 other species some of which may be possible sea-grass epiphytes. To separate species go to Pictured keys: narrow branched red algae and trich Pictured keys: Laurencia and Chondrophycus
t sp t sp
fertile terminal branches, deeply stained spores (tetrasporangia, t sp) in lines down whole plants on a sea-grass leaf spores , bright flecks along branches (arrowed) branches, hair-tufts (trichoblasts, tr) due to cell wall thickenings in core cells protruding out of terminal pits
R2.3: Chondria species there are 16 other species some of which may be possible sea-grass epiphytes. To separate species go to Pictured keys: narrow branched red algae and Pictured keys: Chondria and Husseya
tr
p
p
Chondria angustissima plants on a sea-grass leaf partial cross section: central filament male plant: tuft of hairs (trichoblasts, tr), ringed by 5 large (pericentral) cells pads (p) producing spermatia, unique to the genus
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R2.4: Mychodea pusilla
Right: plants on Amphibolis stems
Far right, upper: colourised magnified view of a preserved (bleached) specimen showing pointed tips, swellings containing female organs (cystocarps) Far right, lower: cross section, central filament (c fil) partly obscured by a ring of fine threads, few large inner cells, smaller coloured outer cells
! c fil can easily be mistaken for the next genus, Dicranema
R2.5: Dicranema cincinnalis
Right: preserved (bleached) plants on Amphibolis stems, hooked tips prominent
Far right: cross section, central region of many filaments, numerous larger cells, outer layer of small coloured cells
R2.6: Dicranema revolutum
Right: plants on Amphibolis stems, hooked tips absent, plants generally larger than D. cincinnalis
Far right: cross section, central region of many filaments, numerous larger cells, outer layer of small coloured cells
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Baldock, R N (2020). Seagrass epiphytes at a glance. 26pp. Algae Revealed. Adelaide: State Herbarium of South Australia flora.sa.gov.au/algae_revealed 21
R2.7: Delisea hypneoides there are 4 other species some of which may be possible sea-grass epiphytes. Go to Pictured keys: narrow branched red algae and Groups at a glance: Bonnemaisoniaceae
cyst
Left : cross section, central filament (arrowed) ringed by smaller cells Centre: whole plants Far right, upper: growing tip Far right lower: female organ (cystocarp, cyst) embedded in tip
R2.8: Dudresnaya australis on Amphibolis stems
Dudresnaya australis Left: whole plants Centre: magnified surface view Right: tissue squash, central filament of large cells, branched chains of small cells at the surface
R2.9 Gloiophloea scinaioides on Amphibolis stems. Also found in Pictured keys slimy red algae in this Webpage
plants slimy when fresh
Right: whole plant Far right: tissue squash, core of twisted filaments branching outwards, ending in branched chains of coloured cells
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R3: RIBBON AND BROAD BLADED RED ALGAE go to Pictured keys ..... strap-like and broad-leaved Red algae on this Website
R3.1: Kraftia dichotoma: 2 disparate stages – sexual and may occur on Amphibolis stems
Upper images: sexual plant, on an Amphibolis stem Left: whole sexual plant on Amphibolis stem Centre: tissue squash, central fine filament, mass of branched chains of small coloured cells at the surface Right: prominent hairs emerging from surface cells Lower images: spore plant, encrusting an Amphibolis stem Far left: whole plants Left: cross section through the crust consisting of columns of small cells and spore sacs (some extruded in this image), each sac containing a stack of 4 spores
R3.2: Haloplegma preissii on Amphibolis stems, also common on coralline algae
Right: flat-branched, felty plants Far right: stained detail of the plant tip showing the filamentous web-like structure
R3.3: Thuretia quercifolia on Amphibolis stems
Right: whole plants Centre: detail of jagged edges and veins of blades Right: blade tip
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Baldock, R N (2020). Seagrass epiphytes at a glance. 26pp. Algae Revealed. Adelaide: State Herbarium of South Australia flora.sa.gov.au/algae_revealed 23
R3.4: Dictyomenia tridens on Amphibolis stems
Left: detail of blades pointed margins, veins running to the ends of the points Right: whole plant
R3.5: Pollexfenia pedicellata on Amphibolis stems Left: whole plant Centre: detail of blade, flecked with hair- Right: microscopic surface view of a tufts (trichoblasts) hair tuft tufts (trichoblasts)
R3.6: Callophyllis rangiferina on Amphibolis stems
Right: whole plant Far right: detail of flat branching pattern
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Baldock, R N (2020). Seagrass epiphytes at a glance. 26pp. Algae Revealed. Adelaide: State Herbarium of South Australia flora.sa.gov.au/algae_revealed 24
R4: BEAD-LIKE RED ALGAE Found also in …Groups at a glance: Bead-like red algae on this Website
R4.1: Griffithsia. Several small species separated mainly on sporangial features are possible epiphytes. The whole plant consists of chains of large, naked cells (see also ..Groups at a glance: Griffithsia, on this Website
Griffithsia monilis
inv
inv
Highly magnified, minute sporangial clusters from the constriction between Whole plant Detail of stained cells, sporangial clusters vegetative cells: showing the peripheral in the constriction between vegetative cells involucral cells (inv)
Griffithsia ovalis
Right: whole plant on sea-grass leaf
Far right: highly magnified, minute, darkly stained sporangial clusters from the constriction inv
between vegetative cells: showing the inv peripheral involucral cells (inv) inv inv
R4.2:Coeloclonium. Three species are found commonly on Sea-grasses. Branches are multi-cellular and pinched into bead-like segments.
Coeloclonium umbellatum (as C. umbellula in the Coeloclonium verticillatum with rings of segments Flora) on a Posidonia leaf
Coeloclonium tasmanicum Left: whole plant. Centre: magnified segment, back-lit to Right: backlit segments branching irregular expose internal spreading filaments arising from a central filament
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Baldock, R N (2020). Seagrass epiphytes at a glance. 26pp. Algae Revealed. Adelaide: State Herbarium of South Australia flora.sa.gov.au/algae_revealed 25
R5: CORALLINE RED ALGAE
R5.1: ENCRUSTING CORALLINE RED ALGAE see also Pictured keys..coralline red algae and ...Groups at a glance: Marine algal crusts ......
Pneophyllum sp crusts on leaves, initially at leaf 1. edges . There are several possible epiphyte species on sea-grasses, and definitive identification requires intricate sectioning of tiny
sporangial pustules. ( see 8.Harvey et al for crustose species, which, although for New Zealand,
are still relevant for southern Australia) Pneophyllum coronatum crusts on leaves
Hydrolithon sp crusts on stems Right: plant not long after germination from a spore (arrowed) divided in a cross-
shaped pattern Far right: mature crusts wrapped around stems of Amphibolis
R5.2: JOINTED CORALLINE RED ALGAE see also Pictured keys..coralline red algae.
Jania species
plants with forked branching, reproductive swellings at the join of forks
Right: Jania minuta
Far right: Jania micrarthrodia
Jania minuta two magnifications of bleached, matted
clumps on stems of Amphibolis antarctica (scale is in mm)
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Baldock, R N (2020). Seagrass epiphytes at a glance. 26pp. Algae Revealed. Adelaide: State Herbarium of South Australia flora.sa.gov.au/algae_revealed 26
Metagoniolithon species
Side branches form in rings from joints on the cylindrical main (axial) branches
Metagoniolithon stelliferum Right: preserved (bleached) specimen
Far right: detail of branching
pattern with up to 8 radiating, short, side branches arising in a ring
Metagoniolithon chara (not illustrated) is a similar species also found on sea- grasses. 2-3 short side branches arise almost vertically in a ring at each joint of main branches (axes), and each of the axial cells is about the same length, so that side branches end at the same level, producing a banding effect in the plant overall, although this is often difficult to detect because the fragile plant is easily damaged and side branches may be lost.
§Haliptilon roseum Plants with flat branched/pinnate main branches (axes), side branches forked, cylindrical, sometimes so prolific that the pinnate main branches are obscured. A common epiphyte of sea-grasses, and highly variable in form.
Left: crowded plants, pinnate branching Centre: detail of flat main branches and Right: detail of reproductive swellings obvious short, cylindrical side branches topped by cylindrical branches
Right: plant in which the prolific side branches obscure the pinnate branching of axes Far right: male plant, spindle-shaped reproductive organs, prolific side branches
§ recent DNA analysis has indicated Haliptilon roseum is more closely allied to the genus Jania with the new binomial Jania rosea
Baldock, R N (2020). Seagrass epiphytes at a glance. 26pp. Algae Revealed. Adelaide: State Herbarium of South Australia flora.sa.gov.au/algae_revealed